GitLab

Replace TestDisplaySnapshot with FakeDisplaySnapshot in tests.
FakeDisplaySnapshot has builder that makes it more readable. Delete an
unncessary build target along with TestDisplaySnapshot.

Tests should be unchanged for the most part. One test was split into two
tests where two very different behaviours were being checked.

Also update tests to use C++11 features where possible. Mostly replacing
raw pointers with unique_ptr<> and NULL with nullptr.

BUG=none

Review-Url: https://codereview.chromium.org/2407153008
Cr-Commit-Position: refs/heads/master@{#427147}